03 Radar Flashcards
ATPL RADIO
What does it mean if a transponder receives a P2 pulse which is stronger than P1 and P3 pulses?
The transponder responses will be suppressed for a short time interval.
When, and from which station, is a Special Position Identification (SPI) pulse sent?
From the aircraft transponder upon selection of the IDENT button by the pilot.
The main factor which determines the minimum range that can be measured by a pulsed radar is pulse:
length
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The minimum range of a radar is determined by the pulse length (or pulse width). Pulse repetition/recurrence frequency defines the maximum unambiguous range of a radar.
Which of the following equipments works on the interrogator/transponder principle?
Secondary Surveillance Radar (SSR)
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Secondary surveillance radar (SSR) use a transponder in the aircraft that replies to interrogation pulses from the ground station.
With regard to SSR
the interrogator is on the ground and the transponder is in the aircraft
Surface movement radar operates mainly in the SHF band as opposed to the EHF band. This is because:
EHF is absorbed and scattered by moisture in the air. Use of SHF reduces this problem
When both SSR and primary radar is presented on the controller’s display:
the primary radar information is more accurate in bearing and distance
In an Airborne Weather Radar that has a colour cathode ray tube (CRT) the areas of greatest turbulence are indicated on the screen by:
colour zones being closest together
Which of the following weather returns displayed on an Airborne Weather Radar should be avoided?
Fingers, Hooks, Scallops
Refer to the annex.
On control knob ‘3’, what does ‘MAP’ mode mean?
The ground/terrain will be displayed.
To improve the detection of precipitation area(s) in e.g. thunderstorms, in which the top of the cloud lies at or slightly above the level of flight,
the tilt setting should be lower when the aircraft climbs to a higher altitude.
In which mode of operation does the aircraft weather radar use a cosecant radiation pattern.
MAPPING
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The airborne weather radar use a cosecant square, fan shaped radiation pattern for ground mapping (up to approximately 70 nm range).
Considering a primary radar system, what kind of aerials are used?
One directional antenna both for transmitting and for receiving.
In order to be able to penetrate cloud, a primary radar signal must have:
a high frequency
What is the maximum number of Secondary Surveillance Radar (SSR) transponder codes in Mode A?
4096
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The secondary surveillance radar (SSR) transponder has a code selection of 0000 to 7777, where 0 to 7 gives 8 possible numbers, and four digits gives 84 = 4096 combinations.
A ground radar transmitting at a PRF of 1200 pulses/second will have a maximum unambiguous range of approximately:
67 NM
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To find the maximum unambiguous range for a radar based on PRF, the formula to use is:
Maximum Unambiguous Range = Speed of Light / 2 x PRF
MODE S
How does a ground interrogation signal (Mode A and C) get transmitted to a transponder?
in form of pairs of interrogative pulses with an additional control pulse.
In relation to primary radar, what does the term Pulse Recurrence Frequency signify?
The number of pulses transmitted per second.
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Pulse recurrence/repetition frequency (PRF) is the number of pulses transmitted per second. Pulse recurrence/repetition interval (PRI) is the time between two successive pulses.
Which one of the following Secondary Surveillance Radar (SSR) codes should be used by aircraft entering airspace from an area where SSR operation has not been required?
2000
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The SSR code ‘2000’ should be used by aircraft entering airspace from an area where SSR operation has not been required.
Airborne Weather Radar has been primarily developed to detect
the kinds of precipitation which are usually accompanied by turbulence.
A mode A/C transponder receives a P2 pulse from which the amplitude is larger than that of the P1 and P3 pulse. Why is this?
The transonder is located in the direction of one of the side lobes of the interrogator antenna.
Attenuation of radio waves means:
The weakening of the radiated waves
Which of the following equipment uses primary radar principles?
Airborne weather radar (AWR)
A frequency of 10 GHz is considered to be the optimum for use in an airborne weather radar system because:
the larger water droplets will give good echoes and the antenna can be kept relatively small